Semiconductor elements such as an IGBT (insulated gate bipolar transistor) and a power MOSFET (metal oxide semiconductor field effect transistor) are incorporated into a semiconductor device. This type of semiconductor element is a switching device which can control a large current at high speeds.
A semiconductor element, for example, an IGBT, is arranged with a collector region, a base region, an emitter region, a gate insulation film and a gate electrode. The collector region is formed by epitaxial growth on one main surface of a substrate or by diffusion in one main surface part of the substrate. The base region is formed in the other main part of the substrate. The emitter region is formed on the surface part of the base region. The gate insulation film is formed on at least the surface of the base region and the gate electrode is formed on the gate insulation film.
By forming the gate electrode in the shape of a stripe, an IGBT with a stripe structure having a high resistance and small gate capacitance is adopted as a semiconductor element. In the IGBT which adopts this structure, the gate electrode extends on the substrate main surface in a gate length direction, a plurality of the gate electrodes is arranged in series at fixed intervals in the gate width direction, and seen from above, one part of the surface of the emitter region and base region is exposed in a stripe shape in a gate length direction in between the gate electrodes in the gate width direction. An emitter electrode (emitter wiring) is electrically connected to the emitter region and base region in which the surface is exposed. The emitter electrode is formed on an interlayer insulation film between gate electrodes and the interlayer insulation film covers the gate electrode and has a stripe shaped aperture (contact hole) in a gate length direction on the region of the part of the emitter region and base region which is exposed. That is, in a cross section taken in a gate width direction, a plane shape of an interlayer insulation film of a projection which has a gap in adjacent interlayer insulation films by this aperture becomes a stripe shape the same as the plane shape of the gate electrode. Because it is possible to increase the contact area between the emitter electrode and the emitter region, base region and increase current capacitance in an IGBT which has this type of stripe structure, it is possible to reduce the occurrence of electrical filed concentration and realize a large current and high resistance.
An emitter electrode of an IGBT is electrically connected to an emitter lead (external terminal) via bonding wire, and a gate electrode is similarly electrically connected to a gate lead via bonding wire. A collector electrode, for example a collector electrode arranged on the other main surface of a substrate is electrically connected to a collector lead. A wire bonding device is generally used for the bonding wire and bonded by thermal compression combined with ultrasonic vibration. In addition, IGBT is sealed together with the inner parts of each lead and assembled as a semiconductor device.
Furthermore, this type of semiconductor device is described in, for example, patent document 1 and patent document 2 stated below.
[Patent Citation 1]
Japanese Laid Open Patent H10-22322
[Patent Citation 2]
Japanese Laid Open Patent 2002-222826